It is known that socks are manufactured with circular machines having one or two needle cylinders. The knitting starts from the elastic hem and finishes at the toe side which is left open to be closed afterwards by suitable seamer-linker machines. More specifically, it is known that after the formation of the necessary ranks, or knit courses, for the sock toe, a number of waste knit course of a so called "unthreading" edge is formed, usually of shaved knit one centimeter high, to avoid ladders during the seaming of the toe. Depending on the type of machine being used, the socks are produced:
a) one after the other. In this case, the last unthreading knit course of the toe is connected to the first knit course of the elastic hem of the next sock through a resistant, smooth and well visible thread which is worked with a feeding unit other than that for the elastic hem, and which is to be manually removed to separate one sock from the other prior to the seaming of the toe; PA1 b) one separate from the other. This procedure is used mostly in the single- or two-cylinder circular machines which are provided with an automatic device for the separation of the manufactured socks. PA1 lowering the needles of the second partial course, with the sinkers being open, so as to move the stitches of the first and second partial courses to a level beneath that of the sinkers nib of the machine; PA1 lifting the needles of the second partial course, with the sinkers being closed, so that the corresponding pairs of stitches of the first and second partial courses will result retained by the sinkers at a predetermined position relative to the stem of the respective needles; PA1 lifting farther the needles of the second partial course until all the corresponding pairs of stitches will reach the operating level of the transfer means of the first partial course, so as to have the stitches retained by the means; PA1 lowering the needles of the second partial course so as to allow the article to have the stitches of the first and second partial courses removed from the transfer means, that is, to clear the article of the knitting needles; PA1 transferring the article, with the thus retained stitches, so as to locate it at a predetermined distance form the knitting cylinder; PA1 disposing the thus transferred stitches so as to have them angularly equidistant, with a circular pitch that can be varied, that is, selected according to the required degree of hook-up fineness; PA1 linking the corresponding pairs of stitches thus disposed, by means of a linking needle, to form a chain and, upon completion of the hook-up, making one or more knots for closing the chain; PA1 cutting the hook-up thread; PA1 releasing the thus joined pairs of stitches of the first and second partial courses, to allow the article to be removed in its final, right-side out condition. PA1 cam means for operating the lifting and respectively the lowering of a predetermined number of needles of a first and second partial courses of stitches, which means are in operative condition when the knitting cams are inoperative, and vice versa; PA1 means for removing the stitches of the first partial course and overturning them through 180.degree. about a diametral axis of the needles cylinder and, besides, for removing the pairs of corresponding stitches from the needles of the second partial course, with a pair of spikes for each stitch, respectively pair of corresponding stitches, and at least a corresponding opening respectively closing peg, which pegs are slidingly received within corresponding slots of a semicircular sector: the sector being rotatively mounted to perform a 180.degree. angular displacement thereof in both directions about a diametral axis of the needles cylinder at a position overlying the sinkers of the machine producing the article and supported by members allowing the transfer thereof from the knitting station to a station for linking the article toe; PA1 cam means, located in correspondence of the knitting station, for driving the spikes and respectively pegs within the corresponding slots of the oscillating sector; PA1 cam means for operating the 180.degree. overturning in both directions of the semicircular sector about a diametral axis of the needles cylinder; PA1 cam means for maintaining the sinker housing of the circular machine at a predetermined and constant angular position; PA1 an actuation cylinder for operating the transfer of the member supporting the semicircular sector from the knitting station to the station for linking the article toe; PA1 cam means, in correspondence of the knitting station, for driving the spikes and respectively pegs during the steps of presetting the stitches for the linking thereof and of expelling the finished product; PA1 a seamer-linker to carry out the seaming-linking of pairs of corresponding stitches and making the knots to close the seaming-linking line; PA1 means for finally cutting the seaming-linking thread; PA1 means for holding the end of the linking thread after the cutting thereof.
Afterwards, each sock must be turned inside out to allow for the seaming on the reverse side thereof. Then, the toe is closed by removing the waste edge and sewing the stitches of the last semirank, or partial course, of the back of the foot together with the stitches of the last partial course of the sole.
However, seaming the toe of the socks outside the machine which make them brings about an increase in the time and cost of production, mainly as a consequence of the numerous intermediate operations to be carried out after the completion of the knitting and before the very seaming of the toe, intermediate operations which include, for example, the removal of the socks and the transfer thereof to the relevant stocking stores where they are selected according to their color and/or size.
All this implies, in fact, relying on skilled personnel who carry out and supervise these operations, and the provision of sufficiently large premises for sitting the machines and selectively storing the socks. Moreover, in case of large numbers of thus formed socks, the amount of yarn which is wasted in the manufacturing of the socks and the subsequent removal of the waste edge, results significantly high costs. Therefore, the relevant cost is economically ineffective and heavily detrimental to the yield of the traditional manufacturing plants.
The Italian patent application No. FI92A194 discloses a method for seaming two front edges of a knitted tubular article, especially a sock. The method comprising the step of manufacturing a knitted tubular article, by means of a one-cylinder circular machine, by starting from the elastic hem and finishing on the side of the toe which is left open. The method further comprises the following operating steps:--lifting a predetermined number of needles of a first partial course, together with the respective stitches, up to a predetermined level: the term partial course referring to a plurality of adjacent stitches belonging to an edge of the article toe;--lifting a predetermined number of needles of a second partial course, together with the respective stitches thereof, to the same level as those of the first partial course;--removing the stitches of the first partial course, lowering the corresponding needles and transferring the stitches, through a 180.degree. overturning thereof about a horizontal diametral axis of the needles cylinder, so that each thus overturned stitch will fit the relevant needle of the second partial course;--releasing the stitches of the first partial course from the relevant transfer means and moving the thus superimposed pairs of stitches to a level suitable for the linking thereof;--rotating the needles cylinder intermittently to insert step-by-step a linking needle into a pair of thus disposed stitches by supplying it, without solution of continuity, with the thread used for knitting the article, and then removing it to form a hook-up plain-chain stitch.
The same document discloses an apparatus for carrying out the above method, which comprises:--cam means for vertically moving a predetermined number of needles of a first and second partial courses of stitches of the toe of the article in the course of formation, which means are in operating condition when the knitting cams of the circular machine are in inoperative condition, and vice versa;--means for removing the stitches of the first partial course and overturning them through 180.degree. about a diametral horizontal axis of the needles cylinder, with a pair of spikes for each stitch and at least a corresponding opening and respectively closing peg, each of which is slidingly housed within a corresponding slots of a semicircular sector: the sector being mounted for a 180.degree. displacement in both directions about a diametral horizontal axis of the needles cylinder, in a position above the sinkers of the machine;--means for making the semicircular sector solid to the needles cylinder, with a radial shutter sliding between two positions of locking and respectively releasing the sector with respect to the needles cylinder, but in a constant and preset spatial location;--fork means for locking the sinker housing during the horizontal rotation of the semicircular sector in conjunction with the needles cylinder, the fork means being activated by corresponding cam means solid to the support of the semicircular sector;--means for linking the paired and superimposed stitches being loaded on the needles of the second partial course by means of a linking bearded needle, with a crochet operatively associated to the needle and located on the opposite side thereof with respect to the stitches, and with a wheel or skid for pressing down the fabric and holding the stitches in linking attitude during the linking operation. The wheel or skid being located on the same side of the linking needle with respect to the knitting needles. The whole of the above means being disposed on top and sideways of the needles cylinder.
The above operating method, although making it possible to provide a finished product of good quality, implies the need of leaving the knitting needles inserted, the same needles supporting the; stitches of the article during the linking operation inside the tuck loops which constitute the seam stitches, so that the hook-up line joining the edges of the article are slightly expanded. The shed for sewing the edges are the same as the knitting one, instead of being smaller as necessary to achieve a closer and more elastic seaming and make, therefore, a better quality article. Besides, the apparatus for implementing the known method is of remarkable constructional complexity, especially in relation to the large number of elements disposed in correspondence of the knitting head of the circular machine. This implies, above all, the need of providing a strict procedure for the integration and coordination of the apparatus with the circular machine which makes the article. Also as a reduced level of modularity is caused, that is, a substantially reduced possibility of adding further elements able to improve the quality of the product as far as the knitting and/or final hook-up is concerned. Further this greatly limits the access to the individual components of the linking device. All this at the expense of simplicity and cost of intervention for assembling and/or up-keeping the circular machine and/or the same apparatus for the linking of the toe. Moreover, the circular machines for the knitting of the article must be properly suited, from the architectural, structural-mechanical and operational point of view, to the specific disposition of the means provided to carry out the above toe-closing method. In view of the numerous constructional and functional differences which differentiate the various circular machines known at present, this represents a drawback owing to the limitation of interchangeability degree of the apparatus which, accordingly, must be designed to meet the specific requirements of the knitting machine it is to make part of.